Start with a rectangular sheet of paper
Fold the paper in half lengthwise
Unfold it and crease the center line firmly
Fold the top two corners down to the center line
Fold the new top edges down again to the center line
Fold the plane in half along the center line
Fold each wing down evenly
Adjust the wings so they are level
Make small upward folds at the wingtips
Press all creases sharply
Test the plane with a smooth throw